Mullite sintered body, method for producing the same, and composite substrate

Patent metadata

Field	Value
Publication number	US-2016185668-A1
Application number	US-201615064968-A
Country	US
Kind code	A1
Filing date	Mar 9, 2016
Priority date	Jun 6, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

A mullite sintered body according to the present invention has an impurity element content of 1% by mass or less and contains sintered mullite grains having an average grain size of 8 μm or less. When a surface of the mullite sintered body is finished by polishing, pores in the surface have an average largest pore length of 0.4 μm or less. The surface preferably has a center line average surface roughness (Ra) of 3 nm or less. The surface preferably has a maximum peak height (Rp) of 30 nm or less. The number of pores in the surface is preferably 10 or less per unit area of 4 μm×4 μm.

First claim

What is claimed is:

1 . A mullite sintered body having an impurity element content of 1% by mass or less,
the mullite sintered body containing sintered mullite grains having an average grain size of 8 μm or less, wherein pores present in a surface thereof finished by polishing have an average largest pore length of 0.4 μm or less:

2 . The mullite sintered body according to claim 1 , wherein the surface has a center line average surface roughness (Ra) of 3 nm or less.

3 . The mullite sintered body according to claim 1 , wherein the maximum peak height (Rp) of the surface is 30 nm or less.

4 . The mullite sintered body according to claim 1 , wherein the number of pores in the surface is 10 or less per unit area of 4 μm×4 μm.

5 . A mullite sintered body according to claim 1 , wherein the mullite sintered body has a 4-point flexural strength of 280 MPa or more.

6 . The mullite sintered body according to claim 1 , wherein the impurity element content is 0.5% by mass or less.

7 . The mullite sintered body according to claim 1 , wherein when the mullite sintered body is formed into a plate having a thickness of 0.1 mm, the plate has a total light transmittance of 20% or more to light having a wavelength of 550 nm.

8 . A method for producing a mullite sintered body, the method comprising compacting a mullite raw material powder with a purity of 99.0% by mass or more (substances to be released by heating are not considered impurities) into a predetermined shape, and sintering the shape by hot press firing at a pressing pressure of 20 kgf/cm 2 to 300 kgf/cm 2 and a firing temperature of 1525° C. to 1700° C.

9 . A composite substrate comprising: a support substrate; and a functional substrate bonded to the support substrate,
wherein the support substrate is made of the mullite sintered body as set forth in claim 1 .

Assignees

• Ngk Insulators Ltd

Inventors

• Isoda Yoshinori
• Sato Yosuke
• Katsuda Yuji

Classifications

• C04B2235/9653

  Translucent or transparent ceramics other than alumina · CPC title

• C04B2237/72

  Forming laminates or joined articles comprising at least two interlayers directly next to each other · CPC title

• C04B35/645

  Pressure sintering · CPC title

• C04B2235/963

  Surface properties, e.g. surface roughness · CPC title

• C04B2235/6565

  Cooling rate · CPC title